//
// Created by 51165 on 2025/10/13.
//
#include <stdio.h>
int main() {
    float sum = 0;
    for (int i = 1; i <= 100; i++) {
        if (i%2 == 0) {
            sum -= 1.0/i;
        }
        else {
            sum += 1.0/i;
        }
    }
    printf("sum = %f\n", sum);
}